19

#19
Added 3 image manipulation modules as per issue 19. 
This is a work in progress, but it passed build and looks OK. Since it takes care of the original issue 19, you can merge it when you merge branch 21.1 , it should go smooth.

Effects:
At the time of this commit, replaced some image fields with croppable image fields, as shown, for instance, here:

Project page
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![project-page-with-image-cropper](https://cloud.githubusercontent.com/assets/5853528/2874411/10f6cd26-d3e7-11e3-9602-e33225fed316.png)

Cropping an image on the node edit page:
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![cropping-images](https://cloud.githubusercontent.com/assets/5853528/2874416/2cdbbccc-d3e7-11e3-88bc-0616b41c65c8.png)